Troughton & Simms Theodolite

This 30-inch theodolite was made by Troughton & Simms in London for the U. S. Coast Survey, probably in the late 1840s. Only the unusually short trunnions, telescope, small vertical circle, and micrometer eyepiece remain. The standards, graduated horizontal circle, and tripod base are missing.
Ref: C. A. Schott, "Determination of the Astronomical Azimuth of a Direction," United States Coast Survey Annual Report (1866), Appendix No. 11.
Currently not on view
Object Name
date made
late 1840s
Troughton and Simms
telescope aperture: 2 3/8 in; 6.0325 cm
telescope: 30 in; 76.2 cm
vertical circle: 5 1/2 in; 13.97 cm
trunions: 12 1/2 in; 31.75 cm
place made
United Kingdom: England, London
ID Number
accession number
catalog number
Measuring & Mapping
Surveying and Geodesy
See more items in
Medicine and Science: Physical Sciences
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center
United States Coast Survey. United States Coast Survey Annual Report

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